1. Technical Field
The present embodiments are related to flow shutoff valves for water lines, and, more specifically, self-cleaning flow shutoff valves.
2. Description of Related Art
Shutoff valves to prevent excess flow, such as when a sudden leak occurs downstream of the valve, are well known in the art. Such valves are found in high pressure hydraulic systems, fueling systems and critical gas systems. Such valves are relatively expensive because of complicated housings and/or valve elements, costly materials, and precision machining requirements.
Public water supplies to appliances, sinks and toilets are often connected to manual shutoff valves that are installed in the water line. The conventional means for connecting the manual shutoff valves to an appliance, or the like, are typically through flexible hoses. Personal experience and insurance statistics suggest that a great many such manual shutoff valves are not closed when appliances are not in use. Consequently, the integrity of the flexible hoses remains the only means of containing water pressure to an appliance. Insurance companies in North America report payments amounting to hundreds of millions of dollars annually that solely result from broken appliance hoses. Other statistics for sinks and toilet systems, not using flexible hoses, but which are subject to leaking or other problems, are similar.
The shutoff valves used for hydraulics, fuels and gases are out of practical range for use with appliances. However, other solutions have been applied to the problem of flooding from appliance hoses in a number of ways. Electrical sensors, timers and valve drives have been devised. Mechanical devices have also been employed, but are complicated, expensive and/or limited in their use.
One problem that must be addressed by shutoff devices is the presence of particles and hardness in the water supply, which can accumulate to disable such valves. The utility of most shutoff valves is as an emergency device with very infrequent actuation. Consequently, interfering deposits can build up with continued flow through the valve without actuation and result in malfunction of the valve when needed.